rs1057516451

chr11-66514468-ACT-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_024649.5(BBS1):c.223_224del(p.Leu75GlyfsTer23) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,866 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. L75L) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: BBS1 NM_024649.5 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:7
• Conservation: PhyloP100: 0.219

Genes affected

BBS1 (HGNC:966): (Bardet-Biedl syndrome 1) Mutations in this gene have been observed in patients with the major form (type 1) of Bardet-Biedl syndrome. The encoded protein may play a role in eye, limb, cardiac and reproductive system development. [provided by RefSeq, Jul 2008]

(HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-66514468-ACT-A is Pathogenic according to our data. Variant chr11-66514468-ACT-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 370389.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-66514468-ACT-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BBS1	NM_024649.5	c.223_224del	p.Leu75GlyfsTer23	frameshift_variant	4/17	ENST00000318312.12

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BBS1	ENST00000318312.12	c.223_224del	p.Leu75GlyfsTer23	frameshift_variant	4/17	1	NM_024649.5	P1
	ENST00000658548.1	n.1739_1740del		non_coding_transcript_exon_variant	2/2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461866 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 727234

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:7

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Bardet-Biedl syndrome 1 Pathogenic:4

Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	May 08, 2020	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Feb 02, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Jun 30, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 20, 2023	- -

Bardet-Biedl syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	May 25, 2022	Variant summary: BBS1 c.223_224delCT (p.Leu75GlyfsX23) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory. The variant was absent in 251146 control chromosomes (gnomAD). c.223_224delCT has been reported in the literature in individuals affected with Bardet-Biedl Syndrome (Beales_2003, Janssen_2011, Stone_2017). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Five ClinVar submitters (evaluation after 2014) cite the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Dec 21, 2023	This sequence change creates a premature translational stop signal (p.Leu75Glyfs*23) in the BBS1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in BBS1 are known to be pathogenic (PMID: 12118255, 21520335, 27032803). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with Bardet-Biedl syndrome (PMID: 12677556, 21052717). This variant is also known as L75fsX98. ClinVar contains an entry for this variant (Variation ID: 370389). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Retinal dystrophy Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Blueprint Genetics

Oct 08, 2017

- -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1057516451; hg19: chr11-66281939;